lagoon with feeder tubes connecting to one end of the diffuser
tubing.
2.4.5.2
Supports
Adjustable supports that allow free longitudinal movement with little or no
lateral or vertical movement shall be provided for the air header piping.
All ferrous metal in the support system shall be galvanized.
2.4.5.3
Airlift Purge System
A plastic airlift, complete with integral plastic air jet, shall be
provided as indicated. The system shall include air supply tubing and
piping connected to the main air header. A control valve on the air supply
pipe shall be provided.
2.4.5.4
Gas Cleaning System
A complete system as required for gas cleaning of the air diffusion system
shall be provided. The system shall have a single valve to control flow to
all points.
2.5
DIFFUSERS
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NOTE: Aeration tanks should be identified on the
drawings. Diffuser performance requirements should
be inserted.
**************************************************************************
2.5.1
Diffuser Performance
Air flow rate shall be [_____] standard L/second per 28.3 cubic meters scfm
per 1000 cubic feet of tank volume.
Oxygen transfer shall be [_____] kg pounds of oxygen per day per 28.3 cubic
meters 1000 cubic feet of tank volume at the specified air flow rate in
clear water at 20 degrees C 68 degrees F and zero dissolved oxygen.
Submergence shall be [_____] mm feet.
Maximum allowable headloss shall be [_____] mm [_____] inches of water,
excluding submergence.
2.5.2
Porous Diffusers
**************************************************************************
NOTE: Delete inapplicable types of diffusers and
materials of construction.
The mean permeability rating of the porous diffusers
will be inserted. The permeability rating is
defined as the number of cubic meters per second
(cfm) of air, at 21.1 degrees C (70 degrees F) and
10 to 25 percent relative humidity, that will pass
through 0.093 square meter (1 square foot) of
diffuser area to the atmosphere, under a
differential pressure equivalent to 508 pascals (2
inches) of water below the plate or within the tube
SECTION 11375A
Page 26
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